Operating system and interrupts（操作系统和中断）

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LVGL is not thread-safe by default.

However, in the following conditions it's valid to call LVGL related functions:

In events. Learn more in Events（事件）.
In lv_timer. Learn more in Timer Handler.

默认情况下，LVGL 非线程安全 。

但是，在以下情况下调用 LVGL 相关函数是有效的：

在事件中。在 Events（事件）中了解更多信息。
在 lv_timer 中。在 Timer Handler 中了解更多信息。

Tasks and threads（任务和线程）

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If you need to use real tasks or threads, you need a mutex which should be invoked before the call of lv_timer_handler() and released after it. Also, you have to use the same mutex in other tasks and threads around every LVGL (lv_...) related function call and code. This way you can use LVGL in a real multitasking environment. Just make use of a mutex to avoid the concurrent calling of LVGL functions.

LVGL has a built-in mutex which can be used with: - lv_lock() and lv_lock_isr() - lv_unlock()

These functions are called internally in lv_timer_handler() and the users need to call them only from their own threads.

To enable lv_lock/lv_unlock LV_USE_OS needs to be set to other than LV_OS_NONE.

Here is some pseudocode to illustrate the concept:

如果你需要使用真正的任务或线程，你需要一个互斥锁，它应该在调用 lv_timer_handler() 之前被调用并在它之后释放。此外，您必须在每个 LVGL (lv_...) 相关函数调用和代码周围的其他任务和线程中使用相同的互斥锁。这样你就可以在真正的多任务环境中使用 LVGL。只需使用互斥锁来避免并发调用 LVGL 函数。

LVGL 有一个内置的互斥锁，可以与以下函数一起使用：

lv_lock() and lv_lock_isr()
lv_unlock()

这些函数在 lv_timer_handler() 中被内部调用，用户只需要在自己的线程中调用它们。

要启用 lv_lock/lv_unlock ，需要将 LV_USE_OS 设置为除 LV_OS_NONE 之外的其他值。

下面是一些伪代码来说明这个概念：

void lvgl_thread(void)
{
    while(1) {
        uint32_t time_till_next;
        time_till_next = lv_timer_handler(); /*lv_lock/lv_unlock is called internally*/
        thread_sleep(time_till_next); /* sleep for a while */
    }
}

void other_thread(void)
{
    /* You must always hold the mutex while using LVGL APIs */
    lv_lock();
    lv_obj_t *img = lv_image_create(lv_screen_active());
    lv_unlock();

    while(1) {
        lv_lock();
        /* change to the next image */
        lv_image_set_src(img, next_image);
        lv_unlock();
        thread_sleep(2000);
    }
}

Interrupts（中断）

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Try to avoid calling LVGL functions from interrupt handlers (except lv_tick_inc() and lv_display_flush_ready()). But if you need to do this you have to disable the interrupt which uses LVGL functions while lv_timer_handler() is running.

It's a better approach to simply set a flag or some value in the interrupt, and periodically check it in an LVGL timer (which is run by lv_timer_handler()).

尽量避免从中断处理程序调用 LVGL 函数（除了 lv_tick_inc() 和 lv_display_flush_ready()）。但是如果你需要这样做，你必须在 lv_timer_handler() 运行时禁用使用 LVGL 函数的中断。

这是一种更好的方法，只需在中断，并在LVGL计时器中定期检查它（由 lv_timer_handler() 运行）。